Titanium-iron eutectic metalizing



P 7, 1970 e. ARUTUNlAN 3,505,094

TITANIUM-IRON EUTECTIC METALIZING Filed May 5. 1966 United States Patent3,505,094 TITANIUM-IRON EUTECTIC METALIZIN G Gregory Arutunian, Detroit,Mich., assignor to the United States of America as represented by theSecretary of the Army Filed May 5, 1966, Ser. No. 548,368 Int. Cl. C23c17/00 US. Cl. 11750 5 Claims ABSTRACT OF THE DISCLOSURE A novel methodfor applying a layer of titanium to a ferrous metal substrate wherebythe ferrous metal substrate is heated in a vacuum or inert atmosphere toa eutectic reaction temperature for said ferrous metal substrate and atitanium sample and manipulating said titanium sample while in contactwith the heated substrate to cause a titanium-ferrous eutectic coatingto be formed on the surface of the ferrous metal substrate.

The invention described herein may be manufactured and used by or forthe Government for governmental purposes without the payment to me ofany royalty thereon.

The present invention relates to a method of producing hard facingcoatings on a base of ferrous metal.

More specifically, the invention relates to a new and novel method ofapplying a greater thickness of corrosion resistant titanium orzirconium metal coating to a ferrous metal than has heretofore beenpossible.

Although titanium has many industrial applications, its most importantchemical property is still its corrosion resistance. This property isattributed to the rapid formation of surface films which are passive innature and resistant to attack in most oxidizing media.

When titanium is mechanically connected to the more anodic metals,accelerated corrosion will occur. This cathodic effect can produceserious problems since it is often found necessary to aflix titanium tocommon structural metals, Where large titanium fixtures are attached tosmall ferrous structures, a severe anodic corrosion will result becauseof the large cathodic area presented by the titanium fixture.

The corrosion of such anodic metals can be greatly reduced by applying acoating of titanium to the metal to be connected to the titaniumstructure.

One successful method of titanium coating of ferrous metals has beenshown by C. W. Horn et al. in Patent No. 3,071,491. In that method, theabsorbed gas in the ferrous metal is driven off by heating the metal ina vacuum. After cooling, a titanium deposit is inserted into the vacuumchamber which is then reevacuated. The titanium is then heated to itsvaporization temperature and the vapor is deposited on the ferrousmetal. The chamber is then cooled and brought to atmospheric pressureand, later, a diffusion process takes place.

One disadvantage to the Horn et al. method is that as the titaniumvapors are deposited on the surface of the ferrous metal, reevaporationof the titanium occurs. This causes the maximum thickness of the coatingto be limited to about 0.0025 inch. This limited thickness, whilesatisfactory for some purposes, is not sufificient for many of todaysmechanical applications for corrosion resistance.

It is therefore an object of this inventio nto provide a method for hardfacing or metalizing ferrous metals.

It is also an object of this invention to provide a method formetalizing a ferrous metal with a titanium coating.

It is a further object of this invention to provide a method forapplying a titanium coating to ferrous metals ice to a greater thicknessthan possible in known methods.

Another object of this invention is to provide a more efiicient andsimple method of applying very thick layers of corrosion resistanttitanium on ferrous metals than were previously obtained by vacuumevaporation processes. 1

It is to be noted that this process may also be used to metalize ferrousmetals with zirconium although the description below will be limited totitanium for the sake of simplicity.

In general, the coating operation embodied in this method comprisesheating a steel base material to 2000 F. F. and placing titanium metalin contact With the steel surface where the coating is desired.

In order to provide an understanding of the principles of the invention,a preferred embodiment shown in the accompanying drawing will bedescribed below. It is understood, however, that no limitation of thescope of the invention is intended thereby since the invention iscapable of being carried out in various alternate ways which will beobvious to one skilled in the art without deviating from the scope orthe spirit of the invention.

In the drawing, the figure shows apparatus which may be used to carryout the method of the invention.

More specifically, the drawing shows, in a vacuum or inert atmosphere10, a high-current, low-voltage transformer 1 connected to copperelectrodes 2. The copper electrodes 2 are, in turn, connected toopposite sides of a ferrous metal 3 which may be a steel plate.

Application of proper values of current and voltage to the steel plateby means of transformer 1 will cause a heating of the steel plate due toits inherent resistance characteristics. With proper preselection of thevoltage and current values, the temperature of the plate can be broughtto within :100 F. of a value of 2000" F.

A titanium wire or rod 4 is then moved across the surface to be coatedby means of rotary push-pull vacuum feed-throughs 5 and 6. Propermanipulation of the feedthroughs will provide a complete sweep of thearea to be coated.

Alternatively, the feed-throughs can be eliminated and the coating canbe accomplished by placing titanium sheet metal on the heated steelsurface without external pressure.

The process causes a slight reduction of the thickness of the steelsample due to the normal function of the eutectic effect. However, thisis more than compensated for by the buildup of the TiFe eutectic coatingwhich, in samples, has been built up to a thickness of inch and more.Basic machining can then be utilized to provide a finished surface onthe coating and to reduce it to the exact desired uniform thickness.

The fusion, and consequently, the smearing of the titanium onto theheated steel surface takes place because of the eutectic reaction at 200F. in spite of the fact that the melting points of steel (2700 F.) andtitanium (3200 F.) are not reached in the process.

Thus, it is obvious that the applicant has presented a new and novelmethod for metalizing ferrous metals with titanium Which represents agreat advance in the field of hard facing. The method is susceptible tovarious changes and modifications within the spirit of the inventionwhich will be obvious to those skilled in the art.

I claim:

1. A process for applying a corrosion resistant coating to a ferrousmetal substrate consisting essentially of the steps of:

(a) evacuating a vacuum chamber containing a ferrous metal and atitanium sample;

(b) heating said ferrous metal substrate to a temperature within therange of 1900 F., to 2100 F.; and

3 4 (c) manipulating said titanium sample so as to smear ReferencesCited it onto the surface of said ferrous metal substrate, UNITED STATESPATENTS thereby causing a titanium-ferrous eutectic coating to be formedat the surface of said ferrous metal. 11162449 11/1915 ECkhaYdt 50 X 2.The process of claim 1 wherein the eutectic coating 5 2,327,739 3/1943Peters 117-200 is formed by the slight eating away of the ferrous metalL 6/1953 PQIIISII 117-200 by reaction with the titanium so as to formthe titanium- 2,732,321 1/1956 et a1 1 750 X ferrous coating. ,744,O325/1956 Highfield 117-119 X 3. The process of claim 1 wherein the heatingof the 2,755,199 7/1956 Rosshelm et a1 3 X ferrous metal is performed bypassing a low volta e, hi h 10 3,120,447 2/ 1964 Buck e 117-22 currentthrough said ferrous sample. 3,297,417 1/ 1967 speel'schnflldef 6 X 4. Aprocess for metallizing a ferrous metal b t t 2,295,701 9/ 1942 Wagner118-76 X consisting essentially of the steps of: 2,424,261 7/ 1947 Tulmln 118-76 X (a) heating said ferrous metal substrate to a eutecticPQREIGN PATENTS reaction temperature for said ferrous metal and atitanium sample in an inert atmosphere; 204054 10/1956 Austraha' (b)placing said titanium sample into contact with said OTHER REFERENCESferrous metal Substrate; and Metals Handbook, ed. by T. Lyman, AmericanSociety (c) manipulating said titanium sample after bringing it intocontact with said ferrous metal substrate as for Metals 1948 1219 1221'TA 1948 to cause a titanium-ferrous eutectic coating to be ALFRED L-LEAVITT, Primary Examiner formed at the surface of said ferrous metalsub- Strate J. R. BATTEN, JR., Asistant Examiner 5. A process inaccordance with claim 4 wherein said U S C1 XR eutectic reactiontemperature ranges from about 19Q0 F. to about 2100 F. 29-196; 117-93,119, 131; 118-50.1, 76

